Effects of non-cropped landscape diversity on spatial dynamics of farmland birds in intensive farming systems
Résumé
Increasing habitats diversity in agricultural landscapes has been proposed as a key measure for reversing
the decline of farmland biodiversity in Europe. However, indicators used for assessing such a potential
compensation effect usually only rely on species diversity and abundance while ignoring variations in
species-specific vulnerability. The extent to which habitat diversity may reverse the decline of specialist
species in Europe to farming systems is thus still unclear. In this study, we investigate whether the effect
of non-cropped habitat diversity on farmland birds’ occurrences was dependent on species’ specialization
for habitats. In particular, we focused on the relative effects of non-cropped habitat diversity on species’
abilities to persist or to colonize new vacant areas. We used a capture–recapture statistical framework to
study the spatial dynamics of 20 farmland bird species in France monitored from 2001 to 2007. We found
that non-cropped landscape diversity reduces both the probabilities that a species becomes extinct
locally and that a species colonizes new vacant areas, and the occupancy rate. Although this suggests a
possible stabilizing effect of the surrounding habitat diversity on species occurrence in farming systems,
the occupancy was only weakly affected. Moreover, we found that the most specialist species were the
more negatively affected by this landscape diversity in terms of colonization abilities. We argue that
accounting for the differences in habitat specialization among farmland species can improve conservation
policies dedicated to the management of landscape diversity.